1. Technical Field
The present invention relates to electroluminescent flexible films incorporated into food or other product packaging. This invention allows product packaging to be illuminated without substantially increasing film thickness or substantially decreasing the film flexibility necessary to conform to varying product shapes. More specifically, this invention can be used with existing product-packaging equipment, such as a vertical form, fill, and seal machine, to incorporate electroluminescent displays into product packaging. More generally, this invention can be used in any product requiring illuminated thin films or illuminated images on thin films.
2. Description of Related Art
There are several examples of embodiments of illuminations on various containers in the prior art. Such designs allow for increased visibility of a design imprinted on the container in dark conditions. Further, illuminated containers are more likely to grab the viewer""s attention than non-illuminated containers. Illuminating decorative designs helps emphasize illuminated parts, much like underlining helps emphasize marked text.
Prior art devices typically utilize bulky light sources for illumination. For example, U.S. Pat. No. 5,567,054 uses a chemiluminescent xe2x80x9cwandxe2x80x9d disposed within a pouch at the base of a bag. The wand consists of two concentric tubes filled with two different chemicals that produce light when mixed. This wand illuminates the bag when the inner, frangible tube is broken to allow the two chemicals to interact. However, the bag requires an additional pouch to contain the wand. The manufacturing process for making the bag would thus require additional manufacturing steps for forming the pouch, placing the wand into the pouch, and heat-sealing the pouch.
A handbag with a removable electroluminescent lamp was disclosed in U.S. Pat. Nos. 5,067,063 and 5,268,827. Electroluminescent technology is discussed in further detail below in reference to U.S. Pat. No. 5,676,451. The electroluminescent lamp used in that invention can illuminate both inside and outside the bag. The lamp, however, must be manually attached to the inside wall of the bag by some mechanical means, such as Velcro or clips. To mass-produce the handbags, additional labor steps would be required to attach the lamp to the inside wall. Alternatively, a separate machine would be needed to make the attachment. Furthermore, the bag requires a separate compartment to contain the battery and DC-to-AC converter. The attachment of an electroluminescent lamp and the addition of the batteries, a converter, a switch, the wiring, and containers to house those materials would unnecessarily decrease the amount of space available inside the bag.
Similarly, U.S. Pat. No. 4,926,296 discloses an illuminated carrying bag with a light bulb attached to a sidewall. Batteries contained in a pouch secured to that sidewall energize the light bulb. Like the invention disclosed in the ""063 and ""827 patents, the illuminating device in the ""296 patent is bulky and requires extra labor and/or equipment to incorporate into existing bags.
In another prior art reference, U.S. Pat. No. 5,676,451, a fabric bag is illuminated with a flexible electroluminescent film strip attached to the exterior of the bag. Electroluminescence is a light emission phenomena resulting from the application of an electric field to prepared phosphor powders sandwiched between sheet-metal electrodes. Electroluminescent strips function with alternating current (AC). Voltage is applied between the front and the back electrode by way of an AC power source and the phosphor particles are excited by the electric field, thereby producing a luminescent energy. The film strip disclosed in the ""451 Patent is energized by a battery and inverter (DC-to-AC converter), both of which are contained in a pouch. Although the electroluminescent film strip is flexible in the preferred embodiment of the ""451 patent and can conform to the changing shape of the bag walls, the electroluminescent film strip still is not part of the wall itself; it still must be mechanically attached. Furthermore, the power source requires its own pouch.
Prior to the current invention, no other invention incorporated electroluminescent materials into self-contained, flexible packaging films for use with product packaged in flexible film packages, such as snack food packaged using a vertical form, fill, and seal machine. Consequently, a need exists for flexible electroluminescent films suitable for use with existing film-packaging equipment or other uses requiring flexible electroluminescent films, such as packaging for chips and other snack food products. Such films should be easily manufactured and readily adaptable to existing form and fill machines. Further, such invention should save space and reduce the necessary amount of raw materials by eliminating the need to attach a separate, exterior light source to the packaging film.
Prior art methods utilized attached light sources that were prone to detachment from shifting container contents or rough handling. Consequently, a need exists for a light source for containers that is not prone to detachment. By incorporating the light source within the packaging film instead of merely attaching it onto the film, such invention would prevent the light source from being knocked loose during shipping or handling. The invention should also be flexible in order to withstand the deformation of containers that occurs during normal shipping and handling.
The proposed invention comprises a flexible electroluminescent film, and packaging derived therefrom, in combination with other elements capable of illuminating graphic designs contained within the film layers. The invention can be used as flexible packaging material and can be used in traditional packaging devices. All the necessary components for illumination are incorporated within a thin film sheet.
In one embodiment of the invention, the flexible electroluminescent film is incorporated within the layers of a bag used to hold chips or other snack food products. Electroluminescent material is sandwiched within various polymer, ink, and moisture-absorbing layers. A thin-film DC power source, a thin-film current inverter, and a thin-film touch-sensitive switch (xe2x80x9cpower systemxe2x80x9d) are all incorporated within the layers of the packaging material. Thus, a single sheet of film incorporating all these features can be fed into a vertical form, fill, and seal machine. The electroluminescent material, various ink layers, and opaque mask layers are arranged in such a manner as to illuminate a graphics image on the formed bag when the power system is activated.
The invention is a great improvement over the prior art for a number of reasons. Incorporating the light source into the enclosure material itself instead of attaching a separate light source saves interior space and leaves more room for product to be enclosed. Having the packaging and light source all in one piece also avoids the problem of having attachments that can be knocked loose during shipping or handling. It also avoids the problem of enclosed items snagging or catching onto the light and/or the power system.
Importantly, having the light source and power system already incorporated into a film sheet saves time and expense for packaging facilities. Whereas prior art solutions required extra machinery and/or labor to attach electroluminescent lamps, no such additions are necessary with this invention. The sheet comprising the flexible electroluminescent film can be assembled on a film converter and used in existing form, filling, and sealing packaging systems for existing product lines.
Incorporating the electroluminescent layers into the packaging layers saves raw material costs by preventing the duplication of materials. In prior art systems involving electroluminescent lamps separately attached to packaging walls, both the lamp and the packaging walls required their own moisture-trapping layers. Because the electroluminescent layers are within the packaging layers, only one set of moisture-trapping layers is necessary.
The above as well as additional features and advantages of the present invention will become apparent in the following written detailed description.